Using the Cross Slide for Threading

The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)

Oh I meant included angle of 29 degrees so 14.5 compound setting. So distance moved times .968 ? So 100 thou in and I'd be less than 4 thou off? That's a maybe mess with maybe not....

Paul
 
What kind of threads are you cutting?
 
To add to this thread... (well not much really)

I always thread using the compound. That's how I was taught & that's what I'm used to. I've tried threading with just the cross slide & it came out fine on aluminum 20 TPI, 304 not so much. I don't like it, just not used to it I guess. I only tried it cause this subject came up a while back on another forum. Never knew it would make a difference for coarser than 20 TPI (good to know) but then again I never did try any coarser than 20 TPI.

I thread harder materials like SS & Ti often. Using the compound gives me better results. As Bob mentioned, another reason I like using the compound cause it's easy to keep track of DOC. When threading with the cross slide I quickly lost track of where I was at. However lots of times I will thread with the compound, then make my final pass with the cross slide.

Threads on Ti 6Al4V (grade 5)

View attachment 241232

View attachment 241231

Nice thread but I really like the knurling on that handle



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there is a thread that I have cut that requires using the cross slide the compound is set at 90 degrees so you can advance the tool bit 1/3 of the way around the thread I was cutting was a triple lead thread that I was cutting for an apprentice project so you had only the cross slide to advance the toolbit bill

I'd have walked the spindle gear (does need it to be divisible by the number of starts though), and used the topslide at the thread angle-minus-a-bit, especially if it was a "foreign" thread, like metric cut with an Imperial leadscrew...

Dave H. (the other one)
 
I would say I learned from this thread...but I need compound DOC VS the dial reading of the compound explained. If this isn't on topic enough I can start a new post....and also relate this 14.5 degree setups. :)

Mike that looks great!
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)
Oh I meant included angle of 29 degrees so 14.5 compound setting. So distance moved times .968 ? So 100 thou in and I'd be less than 4 thou off? That's a maybe mess with maybe not....

Paul
You have the idea, Paul. .968 is closer to .003 off than .004... You will find that this job will also be tactile and visual, using your sight and hearing as well as numbers from equations... The wear will not be even, and the cuts won't be, either... Just be careful and do the best you can, no impetuous moves.
 
The depth of cut is the cosine of the angle times the tool travel. For your 14.5 degree angle, I assume you would set the compound to 7.25 degrees. Then you multiply the distance moved on the compound times .992 to get the achieved depth of cut. (It is really close enough to 1 to be disregarded...)

You have the idea, Paul. .968 is closer to .003 off than .004... You will find that this job will also be tactile and visual, using your sight and hearing as well as numbers from equations... The wear will not be even, and the cuts won't be, either... Just be careful and do the best you can, no impetuous moves.

Wouldn't it make sense to use a 90 degree setup and use only the cross slide on existing threads(Large Acme)? Using a tool that is ground to fit the profile of the majority of the existing screw thread....the most worn part. With the side reliefs done virtually the same. If done really lightly I can't see that it would load up the tool too much. As well, with a follow rest behind the tool.

Closer to .003 :) I knew you'd catch that Bob. This is why I like having discussions with you guys. I can't get that kind of feed back from anything else I do. I think on most of the equations if there isn't a calculator on the Internet for it...basically I'm stumped. :(

Paul
 
i have never cut threads with the crosslide.
i was taught to use the compound @29.5*.
i should try some crosslide threading to see the differences for myself.

i'm a little reticent before starting the process, that the method may not be ideal for 304 stainless steel, which galls terribly.
but i'll give it a go!
As I mentioned below, touch off the tool and set the CS and compound to Zero, advance the compound for the first cut and leave it there, retract the cross slide to clear the thread then return to the beginning, crank the CS back to zero and advance the compound again and leave it there. This has 2 advantages, you do not have to rotate the compound dial several times to clear and it records the depth of cut on the dial. You may have never spent 40 hours per week for several weeks turning threads on a manual lathe but it quickly grows tiresome.
 
As I mentioned below, touch off the tool and set the CS and compound to Zero, advance the compound for the first cut and leave it there, retract the cross slide to clear the thread then return to the beginning, crank the CS back to zero and advance the compound again and leave it there. This has 2 advantages, you do not have to rotate the compound dial several times to clear and it records the depth of cut on the dial. You may have never spent 40 hours per week for several weeks turning threads on a manual lathe but it quickly grows tiresome.
thank you very much for the information Wreck!
no sir, i have not done 40 hours single point threading in a year's time! much less in a week
i'm fortunate that in my normal work, taps and dies get the most work out.
i machine stuff for fun 70% of the time.
i like to learn 100% of the time :)
i appreciate your valuable input

i do have one observation, not directed at anyone specifically, just an observation.

i appears to me ...
you know you are really good at something complicated or involved , when you get bored doing it.
 
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thank you very much for the information Wreck!
no sir, i have not done 40 hours single point threading in a year's time! much less in a week
i'm fortunate that in my normal work, taps and dies get the most work out.
i machine stuff for fun 70% of the time.
i like to learn 100% of the time :)
i appreciate your valuable input
In my normal day any threaded part under 2" Dia. and less then 40" long I do in a NC lathe.

We have a recurring job, 2 1/2-4 X 7" long threads on a 115" long bar of 304 SS, 25 of these will take me over a week to finish on a manual lathe.
Consider yourself lucky mate (-:
 
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